I first got interested in illumination when I was around 12. I built a light with AA batteries and an incandescent bulb inside a round plastic box. I also had a mercury switch in it, so when I rolled it across the floor it would flash on and off. At night it lit up the room. But during the day I could barely see it. How did that work? How did a bright light become dim just because there was other light there? How do you make as much _useful_ light as possible with as little energy as possible? Because incandescent bulbs were terrible in that respect. In high school I discovered LEDs and how efficient they were. At that point they still weren't as good as flourescent light but they were so much easier to use. I built all sorts of things full of flashing LEDs because I thought they looked cool. In college I finally got my hands on some very efficient red LEDs, and I built a red flashlight on top of a 9 volt battery. It was remarkably useful; both bright and small enough to fit in a pocket. It was the first time I realized that LEDs could be used for illumination. But back then you could get efficient red LEDs and sort of efficient green LED's. Together they made a yellowish light. Everyone who worked with LED's knew that the holy grail was a blue LED - a red, green and blue LED could both make white light and any color humans could see by adjusting their intensities. It was how TV's worked, except they used phosphors. We knew that once you had blue LEDs you could make huge and fairly cheap TVs by using LEDs instead of CRTs. And you could make white lights. Around 1990 I found my first blue LED from a surplus place called Hosfelt Electronics. It was a dim not-very-efficient blue LED in a T 1-3/4 housing, but it was absolutely blue and it meant that better ones were coming. I built several "any-color" lights that I could adjust to make any color from warm white to cool white to purple etc. In 1992 I was working on flourescent ballasts at work and put together the most efficent ballast plus bulbs I could find. They were high color rendering 34W tubes from Philips, and they put out a lot of light. And it wasn't the usual cold flourescent light either; it was a warmish white that looked a lot like incandescent light. I used it for a light over my workbench. The ballast was one of the first Advance electronic ballasts as well. Not only was it more efficient, it was dimmable down to 20% - so I could cut back even further on power when I didn't need it to be bright over the workbench. I also started to see compact flourescents start to replace incandescents. They had all sorts of problems - long warm up times, harder to dispose of, some were noisy - but they were a solid 4x improvement in efficiency over incandescents. This was an even bigger deal in warm climates, since air conditioners also had to shoulder the load to cool the incandescents in houses that used them. I changed all the lights in my parent's house out to CFs and they saw a significant drop in their power bill. In 1995 I started to get more efficient blue LEDs and made a few white-light flashlights. Then around 2000 blue LEDs with phosphor backings started to appear. These flouresced red and yellow and thus made the light appear white, at a small loss in efficiency (since you lose energy when you downshift in frequency.) But overall they were more efficient than even compact flourescents, and today they are both cheaper and more efficient than CF's ever were. Nowadays there are amazingly good high intensity LEDs. Petco Park just replaced all their stadium lights with LED's - so now they can be part of the light show, with their instant on/off times. You can buy light tiles you just stick to your wall that gives you not only white light, but any color light you want. We are continually developing illumination that gives us more light, light that looks better, light with more flexibility - and for ever decreasing costs and ever improving efficiencies. And on my wall there is a TV that is made of millions of red, green and blue organic LEDs - the holy grail we talked about way back in college. And similar technology lets you build 100 foot video screens anywhere you want. That old flourescent fixture I built way back when kept moving with me - from my parent's house in New York to a rental house on Long Island, to a house in San Diego, through two apartments, another rental house, the first house I owned and now to my current house, where it hangs over the workbench in the garage. And it finally failed for good after over 30 years of service, with both ends blackened and the filaments so gone that not even the Advance ballast could start them any more. And the bulbs were replaced by LED tubes that are even more efficient and look just as good - so at least the ballast will live on.